How can a 17-year-old young man, who was a Hafiz of the Quran and an excellent student, repent from major sins such as stealing money from the mosque and masturbating in it, and get rid of his continuous addiction to masturbation, given his belief that he is cursed and that Allah has transformed him due to these sins? Is there a solution for his repentance and guidance despite the intensity of his sexual urges and his inability to overcome them?

As long as you have a conscience that pricks you, you are on the right path. Hasten to repent, while having a good opinion of Allah, and supplicate frequently. Be keen on keeping good company, and hasten to marry if possible, or fast if you are unable. If you predominantly suspect that you are afflicted with jinn possession (mass) or the evil eye, perform Ruqya (exorcism) upon yourself. Know that part of the completeness of repentance from theft is to return the stolen item to the mosque's صندوق (fund/treasury). You should consult specialists regarding acne.